CODIMERIZATION OF 2,5-NORBORNADIENE WITH ETHYLENE USING SOLUBLE COBALT AND NICKEL-CATALYSTS

Co(acac)x-Dppe-EtyAl2Cl6-y (x=2, 3;y=3,4) system promotes the codimeri zation of 2,5-norbornadiene (1) with ethylene to give a mixture of 3-v inylnortricyclene (2),5-vinyl-2-norbornene (3) and deltacyclane (4). A maximum turnover (C-9/Co) of 46.3 for the codimers is achieved with t he cobalt system. On Ni(acac)2-Dppe-EtyAl2Cl6-y (y = 2, 3) system 1 an d ethylene selectively codimerize to give 3 and 5-ethylidene-2-norborn ene (5) in the temperature range -5 to -30-degrees-C in CH2Cl2 solvent . The influence of various solvents, ligands, Lewis acids and beta-dik etone ligands on yield and selectivity of the products are investigate d. The maximum turnover of this catalyst system for the formation of c odimer is 16.6. The probable mechanisms for formation of the products are delineated.